Customer called and complained about not getting their extra sauce

Even though the order didn't state extra sauce. I made the order, cut the pizzas, cashed them out, and read off the order back to them. They confirmed it, payed for it, and left. Ten minutes later I took the call from them. "I ordered extra sauce online but I don't see any. I only see bread and cheese." I pulled the order up on the computer, read it back to them. He still insisted that he ordered extra sauce. I informed him that it didn't show that on our end, so he got what he ordered. In the end he told me that he was going to call and complain. I never lost my composure. Not once. I even told him about the measuring that PH uses. He wasn't having any of it.